Research on single-phase Power Factor Correction (PFC) technology is towards the trend of high efficiency and high power density, and the totem pole bridgeless PFC topology is proposed in responsive to this trend, as shown in FIG. 1. In the totem pole bridgeless boost converter circuit system, a first bridge arm unit, a second bridge arm unit, and a capacitor Co are connected in parallel, with one connected end connected to the ground; the first bridge arm unit has two working frequency switches S1 and S2 connected in series in the same direction; a second bridge arm unit has two switches S3 and S4 connected in series in the same direction; an AC power supply Vin and an inductor L are connected between the connection point of two diodes and the connection point of two switches.
In the abovementioned totem pole bridgeless PFC circuit system, due to constraints of the topology itself, the totem pole PFC cannot use the fast recovery diode characteristics to improve EMI (Electro Magnetic Interference) as the two-way switch bridgeless PFC does, meanwhile the hard switching characteristics of the CCM (Continuous Conduction Mode) mode cannot meet the growing demand for high efficiency in the industry, therefore the totem pole bridgeless PFC control policy described in this application is based on the TCM (triangular current mode) mode, according to the simple topology of the totem pole, the high power density and high efficiency requirements can be met simultaneously if it is to control to achieve zero voltage switching (ZVS) or valley switching (VS) feature in full input voltage and full load range in the TCM mode.
However, during the process of practicing and studying the abovementioned control policy, the applicants of the present application found that: in the relevant totem pole conversion circuit system, based on the above control idea, it needs to timely and accurately detect the inductor current zero-cross signal of the PFC to achieve the timing control of working frequency switches S1 and S2 and high frequency switches S3 and S4, so as to achieve the ZVS or VS control in the full input voltage and full load range in the TCM mode.